III. Перепишите следующие предложения, определите в них видовременные формы глаголов и укажите их инфинитив; переведите предложения на русский язык (см. образец выполнения 2).
1. Chemistry plays the central role in the life of modern world.
2. Experimentation in chemistry began only in the 17th and 18th centuries.
3. In chemical reactions one or more substances change their chemical composition and form one or more new substances.
4. Analysis is breaking down a compound into simpler substances or elements.
5. These basic concepts have become part of the education required for many professionals including agriculturists, biologists, dentists, physicians, to just a few.
6. Thousands of years ago people valued gold as a rare and beautiful substance.
7. They also understood that gold had a unique ability to resist delay and corrosion.
8. Scientists worked to produce medicines and spirits from raw materials, such as herbs, and in this way improved methods of separating elements by distillation.
9. This experiment will help you become familiar with the lab setup and equipment.
10. Isaac Newton lived in a period when the toxic effects of chemicals were less understood than today.

Plays (play) - Pr.Simple

Began( begin) - Past Simple

Change - Pr.Simple

Is Breaking down (break down) - Pr.Continuous

Have become (become) - Pr.Perfect

Valued (value) - Past Simple

Understood (understand) - Past Simple

Had (Have) - Past Simple

Resist - Pr.Simple

Worked (work) - Past Simple

Produce - Pr.Simple

Improved (improve) - Past Simple

Will help (help) - Future Simple

Lived (live) - Past Simple

Were understood (understand) - Passive voice , past simple.